Dead Disk Doctor Plus for Damaged Media Recovery
All cd/dvd can be degraded over the time with different rates of degradation and this depends on how they are protected against damages also some errors occurs also if the writing method was not very successful on cd/dvd.
Some cd/dvd reader -writer behave differently on scratched media and if you would like go to cdrlabs and read more regarding tests made.
The quality of medias are also important those who are made from phtalocyanine are considered to have a better life cycle than those made from cyanine.
The most common errors that we encounter if we try to copy files from damaged cd/dvd is cyclic redundancy check (crc) errors. CRC is a mathematical method employes during the copy of files from those medias. During the copy of files to hard drives the operating system makes a calculations and returns some numbers which is knows as checksum that is used to identify the files. When the checksum do not much then CRC errors occurs and the file cannot be copied to the hard drive.